Amygdala Volume in Adults with Posttraumatic Stress Disorder: A Meta-Analysis
Brigham Young University, Provo, UT, USA.The Journal of Neuropsychiatry and Clinical Neurosciences (Impact Factor: 2.82). 02/2009; 21(1):5-12. DOI: 10.1176/appi.neuropsych.21.1.5
Posttraumatic stress disorder (PTSD) may be associated with structural abnormalities in the amygdala. To better characterize amygdala volume in PTSD, the authors conducted a meta-analysis comparing amygdala volumes in PTSD patients and comparison subjects. Using electronic databases, the authors found nine studies comparing amygdala volumes in adult subjects with PTSD with amygdala volumes in comparison subjects (participants unexposed to trauma and participants exposed to trauma but without PTSD). Results showed no significant differences in amygdala volumes between the groups. Within each group, the right amygdala was significantly larger than the left, indicating an asymmetrically lateralized amygdala volume that is preserved in trauma exposure and in PTSD.
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- "Therefore, we cannot infer whether the smaller right amygdala volume is specific to childhood trauma. Nonetheless, recent meta-analyses in adult PTSD samples predominantly related to adulthood trauma only showed a tendency towards smaller amygdala volumes or no differences at all between patients and controls (Karl et al., 2006; Woon and Hedges, 2009), possibly indicating that our findings might indeed be specific to childhood trauma. In addition, a recent study demonstrated smaller amygdala and hippocampus volumes in children that were exposed to early life stress (Hanson et al., 2015), while such an association was only found for the hippocampus in adults (Dannlowski et al., 2012). "
ABSTRACT: Hippocampus and amygdala volumes in posttraumatic stress disorder (PTSD) related to childhood trauma are relatively understudied, albeit the potential importance to the disorder. Whereas some studies reported smaller hippocampal volumes, little evidence was found for abnormal amygdala volumes. Here we investigated hippocampus and amygdala volumes and shapes in an adult sample of PTSD patients related to childhood trauma. T1-weighted MR images were acquired from 12 female PTSD patients with trauma related to physical, sexual, and/or emotional abuse before age 18, and from 12 matched controls. Hippocampus and amygdala were segmented, and volumes were calculated and corrected for the total intracranial volume. Additionally, a shape analysis was done on the surface of the structures to explore abnormalities in specific subnuclei. Smaller right amygdala volumes were found in PTSD patients as compared with the controls. This difference appeared to be located specifically in the basolateral and superficial nuclei groups. Severity of sexual abuse during childhood was negatively correlated with the size of the amygdala. No difference in hippocampal volumes was found. Although our results are not conclusive, traumatic events in childhood might impede normal development of the amygdala, which could render a person more vulnerable to develop PTSD later in life. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
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- "The vmPFC is notable for its role in the extinction of fear responses via inhibition of the amygdala (Milad and Quirk, 2012), whereas the hippocampus can contextually limit fear responses via connections to both the amygdala and vmPFC (Maren et al, 2013). Of note, the amygdala, which frequently shows hyperactivation in adult PTSD (Pitman et al, 2012), has not shown any clear structural abnormalities in meta-analyses (Kühn and Gallinat, 2013; Woon and Hedges, 2009). However, a recent study examining a large cohort did find evidence of smaller amygdala volume in adult PTSD (Morey et al, 2012). "
ABSTRACT: Structural brain studies of adult PTSD show reduced gray matter volume (GMV) in fear regulatory areas including the ventromedial prefrontal cortex (vmPFC) and hippocampus. Surprisingly, neither finding has been reported in pediatric PTSD. One possibility is that they represent age-dependent effects that are not fully apparent until adulthood. Additionally, lower resolution MRI and image processing in prior studies may have limited detection of such differences. Here we examine fear circuitry GMV, including age-related differences, using higher resolution MRI in pediatric PTSD vs. healthy youth. In a cross-sectional design, 3T anatomical brain MRI was acquired in 27 medication-free youth with PTSD and 27 healthy non-traumatized youth of comparable age, sex, and IQ. Voxel-based morphometry was used to compare GMV in a priori regions including the medial prefrontal cortex and amygdala/hippocampus. Compared to healthy youth, PTSD youth had reduced GMV but no age-related differences in anterior vmPFC (BA 10/11, Z=4.5), which inversely correlated with PTSD duration. In contrast, while there was no overall group difference in hippocampal volume, a group X age interaction (Z=3.6) was present in the right anterior hippocampus. Here, age positively predicted hippocampal volume in healthy youth but negatively predicted volume in PTSD youth. Within the PTSD group, re-experiencing symptoms inversely correlated with subgenual cingulate (sgACC, Z=3.7) and right anterior hippocampus (Z=3.5) GMV. Pediatric PTSD is associated with abnormal structure of the vmPFC and age-related differences in the hippocampus, regions important in the extinction and contextual gating of fear. Reduced anterior vmPFC volume may confer impaired recovery from illness, consistent with its role in the allocation of attentional resources. In contrast, individual differences in sgACC volume were associated with re-experiencing symptoms, consistent with the role of the sgACC in fear extinction. The negative relationship between age and hippocampal volume in youth with PTSD may suggest an ongoing neurotoxic process over development, which further contributes to illness expression. Future studies employing a longitudinal design would be merited to further explore these possibilities.Neuropsychopharmacology accepted article preview online, 12 September 2014. doi:10.1038/npp.2014.239.
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- "The investigations of PTSD and amygdala volume with the largest samples included PTSD groups with n = 4443 and n = 2844 but were conducted in children and therefore do not generalize well to adults due to developmental changes in brain structure and connectivity. All studies of adults had a sample size of fewer than 20 in the PTSD group, with the majority of studies having 15 or fewer participants [22, 23, 25, 30, 35]. Consistent with our findings and relevant to the core symptom cluster of reexperiencing symptoms in PTSD, smaller amygdala volume was associated with the presence of cancer-related intrusive recollections in a sample of 76 breast cancer survivors . "
ABSTRACT: Objective: In our study we have hypothesized that volume changes of amygdala, hippocampus, and prefrontal cortex are more pronounced in male posttraumatic stress disorder participants. Material and methods: We have conducted a study of 79 male participants who underwent MRI brain scanning. PTSD diagnosis was confirmed in 49 participants. After MRI was taken all scans were software based volume computed and statistically processed. Results: We found that left amygdala is the most significant parameter for distinction between PTSD participants and participants without PTSD. There were no significant differences in volumes of hippocampi and prefrontal cortices. Roc curve method outlined left amygdala AUC = 0.898 (95% CI = 0.830-0.967) and right amygdala AUC = 0.882 (95% CI = 0.810-0.954) in the group of PTSD participants which makes both variables highly statistically significant. Conclusion: The present investigation revealed significant volume decrease of left amygdala in PTSD patients. Concerning important functions of the amygdala and her neuroanatomical connections with other brain structures, we need to increase number of participants to clarify the correlation between impared amygdala and possible other different brain structures in participants with PTSD.